1. Field of the Invention
The present invention relates to a side bar type cylinder lock with a variable key code.
2. Description of the Related Art
When a key of a cylinder lock mounted on a door of a room or of instruments each placed under the control of individual owner, to which key a predetermined key code is allotted, is stolen or lost, or when an employee who knows such a predetermined key code retires from the service, there is a certain risk that a person or ex-employee, who steals or obtains the key itself as his finding or as a key""s replica produced by himself or herself on the basis of the key code, may illegally use the key or key""s replica in unlocking the cylinder lock of the room or of the instruments. In order to lessen the risk of such illegal use of the key or key code by the person or ex-employee, it is necessary to replace an assembly of the cylinder lock and its key with a new assembly or set of cylinder lock and its key, to which assembly another key code is allotted.
However, it is very cumbersome and expensive to replace the cylinder lock having heretofore been used with such a new set, since the cylinder lock to be replaced is mounted on the door of the room or of the instruments each placed under the control of the individual owner. In order to solve this cumbersome and expensive problem of replacement of the cylinder lock, there is provided a conventional side bar type cylinder lock capable of enjoying a variable key code. For example, such a conventional side bar type cylinder lock is disclosed in Japanese Patent application Laid-Open No. Hei 7-197705.
This conventional cylinder lock comprises:
a sleeve-like casing provided, in its inner peripheral surface, with both a side bar receiving concave portion and a retractor receiving concave portion;
a plug rotatably mounted in the sleeve-like casing, wherein the plug is provided with: a keyhole; a reset-key insertion hole; a plurality of tumbler insertion holes each crossing the keyhole; a side bar receiving hole provided in one of opposite ends of each of the tumbler insertion holes; and, a retractor receiving hole provided in the other of the opposite ends of each of the tumbler receiving holes;
a plurality of tumbler plates each slidably received in the tumbler insertion hole, wherein the tumbler plate is provided with a side bar engaging concave portion in one of opposite sides thereof and a saw-toothed engaging portion in the other of the opposite sides;
a plurality of variable tumblers each slidably received in the tumbler insertion hole, wherein: the variable tumbler is provided with a saw-toothed engaged portion in one of its opposite sides and has the saw-toothed engaged portion detachably engaged with the engaging portion of the tumbler plate; and, the variable tumbler is further provided with a key insertion groove which is communicated with the keyhole;
a retractor slidably mounted in the retractor receiving hole, wherein the retractor is provided with: a plurality of guide portions each adapted to guide the variable tumbler into the tumbler insertion hole in parallel to the tumbler insertion hole; and, a reset-key insertion passing hole, wherein the retractor has one of its opposite sides engaged with a key inserted into the key insertion groove and has the other of the opposite sides formed into an engaging projection which is detachably engaged with the retractor receiving concave portion of the sleeve-like casing;
a side bar slidably received in the side bar receiving concave portion of the plug, wherein the side bar has its front end resiliently biased toward the side bar receiving concave portion of the plug in such a manner such that: the front end of the side bar is received in the side bar receiving concave portion of the plug; and, when the side bar is moved in a direction opposite to its biased direction, the side bar has its rear end detachably engaged with side bar engaging concave portion of the tumbler plate; and
a reset key, wherein, when the reset key is inserted into both the reset-key insertion hole of the plug and the reset-key insertion/passing hole of the retractor and rotatably driven therein, the reset key pushes the engaging projection of the retractor in a manner such that the engaging projection of the retractor is forcibly inserted into the retractor receiving concave portion of the sleeve-like casing.
In the conventional cylinder lock with the variable key code having the above construction: since the reset-key insertion hole for driving the retractor is formed in a front surface of the plug in addition to the ordinary keyhole, the conventional cylinder lock with the variable key code is quite different in appearance from the ordinary cylinder lock of a single-keyhole type due to the presence of the reset-key insertion hole. As a result, the conventional cylinder lock with the variable key code tends to enhance tampering of the reset-key insertion hole by an unauthorized person. For example, such an unauthorized person often fills up the reset-key insertion hole with foreign matter, which often makes it impossible for an authorized person or user to change the key code of the conventional cylinder lock. Further, in changing the key code of the conventional cylinder lock, it is difficult for the user to operate the reset key due to interference from the key inserted into the ordinary keyhole which is closest in vicinity to the reset-key insertion hole. Consequently, the conventional cylinder lock with the variable key code is poor in easiness in use.
Further, since the conventional cylinder lock with the variable key code requires many complicated components and therefore is complicated in mechanism for changing the key code, it is not possible to produce the conventional cylinder lock with the variable key code at low cost
Under such circumstances, the present invention was made to solve the problems inherent in the prior art.
Consequently, it is an object of the present invention to provide a side bar type cylinder lock with a variable key code. The cylinder lock of the present invention is provided with a plug. The plug is provided with only one keyhole in its front surface. Due to this, the cylinder lock of the present invention is excellent in appearance and may discourage tampering of its keyhole. Further, the cylinder lock of the present invention is excellent in easiness in use when its key code is changed. Still further, the cylinder lock of the present invention is simple in construction since it does not require a reset key nor a retractor, wherein both the reset key and the retractor are essential components of the conventional cylinder lock capable of changing its key code. Due to this simple construction, it is possible to produce the cylinder lock of the present invention at low cost.
It is another object of the present invention to provide a side bar type cylinder lock with a variable key code, wherein: the cylinder lock of the present invention is provided with a plug and a sleeve-like casing; the plug is rotatably, but not axially slidably, mounted in the sleeve-like casing; and, the plug has its two engaging projections detachably engaged with the sleeve-like casing.
In accordance with a first aspect of the present invention, the above object of the present invention is accomplished by providing:
A side bar type cylinder lock with a variable key code comprising:
a sleeve-like casing (1) provided with both a side bar holder engaging concave portion (2) and a side bar engaging concave portion (5) in an inner peripheral surface of the casing (1);
a plug (6) rotatably, but not axially slidably, mounted in the sleeve-like casing (1), wherein the plug (6) is provided with: a keyhole (7) which opens into a front surface of the plug (6) to axially extend in the plug (6); a plurality of tumbler insertion holes (8) each intersecting the keyhole (7) of the plug (6); a side bar holder receiving hole (9) formed in one of opposite sides of the tumbler insertion holes (8); and, a spring receiving hole (10) formed in the other of the opposite sides of the tumbler insertion holes (8);
a plurality of tumbler plates (11) each slidably mounted in one of the tumbler insertion holes (8) of the plug (6), wherein: the tumbler plate (11) has one of its opposite side surfaces formed into a side end portion (26) provided with a side bar engaging concave portion (12); and, the tumbler plate (11) has the other of the opposite side surfaces formed into an engaging portion (13);
a plurality of variable tumblers (14) each slidably mounted in one of the tumbler insertion hole (8) of the plug (6), wherein the variable tumbler (14) has one of its opposite side surfaces formed into a saw-toothed engaged portion (15) capable of detachably engaging with the engaging portion (13) of the tumbler plate (11), wherein the variable tumbler (14) has its central portion provided with a key passing hole (17) communicating with the keyhole (7);
a spring (18) received in the spring receiving hole (10) of the plug (6) to resiliently bias the variable tumbler (14) toward the inner peripheral surface of the sleeve-like casing (1);
a side bar holder (19) slidably mounted in the side bar holder receiving hole (9) of the plug (6), wherein: the side bar holder (19) has one of its opposite side surfaces bulged outwardly and formed the thus bulged surface into a bulged portion (21) and has its central portion provided with a side bar receiving hole (20); and, when the plug (6) is rotatably driven relative to the sleeve-like casing (1), the bulged portion (21) enters the side bar holder engaging concave hole (2) of the sleeve-like casing (1) to engage with the side bar holder engaging concave hole (2);
a side bar (22) slidably mounted in the side bar receiving hole (20) of the side bar holder (19), wherein: the side bar (22) has its front end portion (23) biased in a biasing direction toward the side bar engaging concave portion (5) of the sleeve-like casing (1) so as to engage therewith; and, when the plug (6) is rotatably driven relative to the sleeve-like casing (1), the side bar (22) is moved in a direction opposite to the biasing direction of the side bar (22) to have its proximal end portion (24) engaged with the side bar engaging concave portion (12) of the tumbler plate (11); and
a spring (25) for biasing the tumbler plate (11) toward the side bar holder (19), wherein: when the plug (6) is rotatably driven relative to the sleeve-like casing (1) to have the bulged portion (21) of the side bar holder (19) oppositely disposed from the side bar holder engaging concave portion (2) of the sleeve-like casing (1), the spring (25) resiliently forces the side end portion (26) of the tumbler plate (11) to enter the side bar holder receiving hole (9) of the plug (6), and resiliently forces the bulged portion (21) of the side bar holder (19) to enter the side bar holder engaging concave portion (2) of the sleeve-like casing (1), and further resiliently forces the engaging portion (13) of the tumbler plate (11) to disengage from the engaged portion (15) of the variable tumbler (14).
In the side bar type cylinder lock having the above construction, preferably: the sleeve-like casing (1) is provided with two variable-tumbler engaging concave portions (3, 4) in its inner peripheral surface; the variable tumbler (14) has one of its end portions formed into a locking projection (16); and, when the front end portion (23) of the side bar (22) is engaged with the side bar engaging concave portion (5) of the sleeve-like casing (1) and the proximal end portion (24) of the side bar (22) abuts against the side end portion (26) of the tumbler plate (11), the locking projection (16) of the variable tumbler (14) is engaged with the variable-tumbler engaging concave portion (3) of the sleeve-like casing (1).